Le Linda T, Loland Vanessa J, Mariano Edward R, Gerancher J C, Wadhwa Anupama N, Renehan Elizabeth M, Sessler Daniel I, Shuster Jonathan J, Theriaque Douglas W, Maldonado Rosalita C, Ilfeld Brian M
Department of Anesthesiology, University of Florida, Gainesville, FL, USA.
Reg Anesth Pain Med. 2008 Nov-Dec;33(6):518-25. doi: 10.1016/j.rapm.2008.05.006.
It is currently unknown if the primary determinant of continuous peripheral nerve block effects is simply total drug dose, or whether local anesthetic concentration and/or volume have an influence. We therefore tested the null hypothesis that providing ropivacaine at different concentrations and rates--but at an equal total basal dose--produces similar effects when used in a continuous interscalene nerve block.
Preoperatively, an anterolateral interscalene perineural catheter was inserted using the anterolateral approach in patients undergoing moderately painful shoulder surgery. Subjects were randomly assigned to receive a postoperative perineural infusion of either 0.2% ropivacaine (basal 8 mL/h, bolus 4 mL) or 0.4% ropivacaine (basal 4 mL/h, bolus 2 mL) through the second postoperative day. Our primary endpoint was the incidence of an insensate hand/finger during the 24 hours beginning the morning following surgery.
The incidence of an insensate hand/finger did not differ between the treatment groups (n = 50) to a statistically significant degree (0.2% ropivacaine, mean [SD] of 0.8 [1.3] times; 0.4% ropivacaine, mean 0.3 [0.6] times; estimated difference = 0.5 episodes, 95% confidence interval, -0.1 to 1.1 episodes; P = .080). However, this is statistically inconclusive given the confidence interval. In contrast, pain (P = .020) and dissatisfaction (P = .011) were greater in patients given 0.4% ropivacaine.
For continuous interscalene nerve blocks, given the statistically inconclusive primary endpoint results and design limitations of the current study, further research on this topic is warranted. In contrast, providing a lower concentration of local anesthetic at a higher basal rate provided superior analgesia.
目前尚不清楚连续周围神经阻滞效果的主要决定因素仅仅是药物总剂量，还是局部麻醉药浓度和/或容量也有影响。因此，我们检验了零假设，即在连续肌间沟神经阻滞中，以不同浓度和速率给予罗哌卡因，但总基础剂量相等时，会产生相似的效果。
术前，采用前外侧入路为中度疼痛性肩部手术患者插入前外侧肌间沟神经周围导管。受试者被随机分配在术后第二天接受通过神经周围导管输注0.2%罗哌卡因（基础速率8 mL/h，推注4 mL）或0.4%罗哌卡因（基础速率4 mL/h，推注2 mL）。我们的主要终点是术后次日上午开始的24小时内手部/手指感觉丧失的发生率。
各治疗组（n = 50）之间手部/手指感觉丧失的发生率在统计学上无显著差异（0.2%罗哌卡因组，平均[标准差]为0.8[1.3]次；0.4%罗哌卡因组，平均0.3[0.6]次；估计差异 = 0.5次，95%置信区间，-0.1至1.1次；P = 0.080）。然而，考虑到置信区间，这在统计学上尚无定论。相比之下，接受0.4%罗哌卡因的患者疼痛（P = 0.020）和不满意程度（P = 0.011）更高。
对于连续肌间沟神经阻滞，鉴于目前研究在统计学上尚无定论的主要终点结果和设计局限性，有必要对该主题进行进一步研究。相比之下，以较高基础速率给予较低浓度的局部麻醉药可提供更好的镇痛效果。
